There could be multiple reasons why you are seeing different views. First, you created a Portal for users. Did you specify this Portal as the HOME PAGE for the users on their profiles directly or on the Profile they are a member of? Most of the time it is due to the Profile you are using and if a user is a member multiple Profiles it may aggregate the permissions. If a user changes a view, the system will remember this as "last view used" and use it the next time you go to that Module or log in.
If this does not help, we may need further information such as an image showing the issue or if this requires private information to be shared, open a ticket.